.pre {
	margin-top: 10px;
	margin-bottom: 10px;
	border-radius: 5px;
	box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;
	width: 100%;
	overflow: hidden;
	font-size: 1.2rem;
}
.pre:before {
	content: "";
	display: block;
	background: url(https://gitee.com/ZLX0326/blogimg/raw/master/mac.png);
	height: 3rem;
	width: 100%;
	background-size: 4rem;
	background-repeat: no-repeat;
	background-color: #282c34;
	margin-bottom: -7px;
	border-radius: 5px;
	background-position: 10px 10px;
}
